Bi-functional compound positively charged at first ph and negatively charged at second ph, solid support comprising the bi-functional compound, and method of isolating nucleic acid using the same

ABSTRACT

Provided are a bi-functional compound that is positively charged at a first pH and negatively charged at a second pH, a solid support having the bi-functional compound immobilized thereon, and a method of isolating a nucleic acid, including: binding the bi-functional compound with a nucleic acid at a first pH and isolating the nucleic acid from the bi-functional compound at a second pH.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.10-2008-0088955, filed on Sep. 9, 2008, and all the benefits accruingtherefrom under 35 U.S.C. 119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND

1. Field

One or more embodiments relate to a bi-functional compound, positivelycharged at a first pH and negatively charged at a second pH, a solidsupport comprising the bi-functional compound, and a method of isolatinga nucleic acid using the same.

2. Description of the Related Art

Methods of isolating a nucleic acid by using a pH-dependent ion exchangematerial typically include, for example isolating a nucleic acid bytreating a solution of the nucleic acid with a material having anionizable group, such as an acidic functional group or basic functionalgroup, which is positively charged at a first pH, thereby binding thenucleic acid, and subsequently releasing the nucleic acid at a second pHthat is higher than the first pH. Examples of materials having such anionizable group include N-2-acetamido-2-aminoethanesulfonic acid(“ACES”), N-2-acetamido-2-imidodiacetic acid (“ADA”),N-trihydroxymethyl-methyl-2-aminoethanesulfonic acid (“TES”) andtris(hydroxymethyl)aminoethane (“Tris”), each of which is a common,commercially available buffer compound. In other methods of isolating anucleic acid, a pH dependent ion exchange material may be used whichincludes a support such as a silica-coated magnetic particle with aplurality of first ion exchange ligands, in which each first ionexchange ligand includes an aromatic hydrocarbon ring, a spacer whichcovalently attaches the ion exchange ligand to the aromatic hydrocarbonring, and a linker which includes an alkylene chain and which isattached to the silica magnetic particle at one end and to the spacer atthe opposite end.

However, despite these methods, there is remains a need for materialswhich bind efficiently to a nucleic acid, and which also efficientlyrelease the nucleic acid in the reaction of isolating the nucleic acid.

SUMMARY

One or more embodiments include a compound that is positively charged ata first pH and negatively charged at a second pH and a substrate onwhich the bi-functional compound is immobilized.

In an embodiment, the bi-functional compound positively charged at afirst pH and negatively charged at a second pH, is represented byFormula I below:

Q-X-Q₁  (Formula I)

wherein Q or Q₁ is a group represented by —X₁—R₁—Y₁ where X₁ is —O—,—S—, or —NR₂— or a combination comprising at least one of the foregoing,where R₂ is hydrogen, halogen, and a substituted or unsubstituted C₁-C₁₀alkyl, R₁ is a substituted or unsubstituted C₁-C₁₀ alkylene, asubstituted or unsubstituted C₃-C₁₀ cycloalkylene, a substituted orunsubstituted C₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀alkynylene, or a combination comprising at least one of the foregoing,Y₁ is a group represented by

where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic group, or Y₁ is a group that is represented by

and has a 4- to 8-membered alicyclic ring or a 6- to 8-membered aromaticring where R₆ and R₇ are each independently hydrogen, halogen, asubstituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, at least one of Q and Q₁ has a primary or secondary aminogroup,

X is a compound represented by

wherein L is a bond, —O—, —CO—, —S—, —SO₂—, —CH₂—, —C(CH₃)₂—, —C(CF₃)₂—,or a combination comprising at least one of the foregoing,

wherein the carbonyl group and the carboxyl group are substituted at anyavailable carbon position except for a ring connection portion,

or a combination comprising at least one of the foregoing, or

a bi-functional compound that is positively charged at a first pH andnegatively charged at a second pH, wherein the bi-functional compound islinked to at least one monomer comprising monomers represented by M0,M1, M2, M3, or a combination comprising at least one of the foregoing,below, and wherein the bi-functional compound comprises at least one ofa monomer with A and at least one of a monomer with B,

wherein A is a group represented by —OH or —X₂—R₁₁—Y₂ where X₂ is O—,—S—, —NR₁₂—, or a combination comprising at least one of the foregoing,where R₁₂ is hydrogen, halogen, a substituted or unsubstituted C₁-C₁₀alkyl, or a combination comprising at least one of the foregoing, R₁₁ isa substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, and Y₂ is —COOH,—SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing,

B is a group represented by —X₃—R₁₃—Y₃ where X₃ is O—, —S—, —NR₁₄—, or acombination comprising at least one of the foregoing, where R₁₄ ishydrogen, halogen, and a substituted or unsubstituted C₁-C₁₀ alkyl, R₁₃is a substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, and a substituted or unsubstituted C₂-C₁₀ alkynylene,or a combination comprising at least one of the foregoing, Y₃ is a grouprepresented by

where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic ring, or Y₃ is a group that is represented by

and has a 4- to 8-membered alicyclic ring or a 6- to 8-membered aromaticring where R₆ and R₇ are each independently hydrogen, halogen, asubstituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, R₈ is a substituted or unsubstituted C₁-C₁₀ alkylene, asubstituted or unsubstituted C₃-C₁₀ cycloalkylene, a substituted orunsubstituted C₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀alkynylene, or a combination comprising at least one of the foregoing,R₉ and R₁₀ are each independently hydrogen, halogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, wherein the bi-functional compound comprising Aand B has a polymerization degree of about 2 to about 30,000.

In another embodiment, a solid support on which a bi-functional compoundis immobilized, includes a substrate, and the bi-functional compoundimmobilized on the substrate.

In another embodiment, a method of isolating a nucleic acid includescontacting a bi-functional compound with a sample comprising a nucleicacid at a first pH and exposing the bi-functional compound with thenucleic acid bound thereto at a second pH that is higher than the firstpH to release the nucleic acid from the bi-functional compound.

In another embodiment, a solid support on which a bi-functional compoundis immobilized, derives from the sequential reaction product of asubstrate, a surface treatment agent, a dianhydride or polyanhydride,and a nitrogen-containing compound, wherein the bi-functional compoundis positively charged at a first pH and negatively charged at a secondpH.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to the like elements throughout. In this regard, thepresent embodiments may have different forms and should not be construedas being limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description.

In this regard, the present embodiments may have different forms andshould not be construed as being limited to the descriptions set forthherein. Accordingly, the embodiments are merely described below, byreferring to the figures, to explain aspects of the present description.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, regions, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, regions, integers, steps,operations, elements, components, and/or groups thereof. All ranges andendpoints reciting the same feature are independently combinable.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

In the chemical structures herein, and unless otherwise indicated, allbonds which terminate without specifying a terminal group are brokenbonds and represent points of attachment to an unspecified group. Forexample, the group

which specifies groups R₃ and R₄ attached to a nitrogen atom, has apoint of attachment through the broken bond to another substructure.

Also in the chemical structures herein, where “halogen” is specified, itwill be understood to mean fluorine, chlorine, bromine, iodine, or acombination comprising at least one of the foregoing. In an exemplaryembodiment, where halogen is specified, the halogen may be fluorine,chlorine, or a combination of these.

One or more embodiments provide a bi-functional compound that ispositively charged at a first pH and negatively charged at a second pH,the compound represented by Formula I below:

Q-X-Q₁  (Formula I)

wherein Q or Q₁ is a group represented by —X₁—R₁—Y₁ where X₁ is —O—,—S—, or —NR₂— or a combination comprising at least one of the foregoing,where R₂ is hydrogen, halogen, a substituted or unsubstituted C₁-C₁₀alkyl, or a combination comprising at least one of the foregoing, R₁ isa substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, Y₁ is a grouprepresented by

where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic group, or Y₁ is a group that is represented by

and has a 4- to 8-membered alicyclic ring or a 6- to 8-membered aromaticring where R₆ and R₇ are each independently hydrogen, halogen with aproviso that R₆ is not halogen, a substituted or unsubstituted C₁-C₁₀alkyl, a substituted or unsubstituted C₃-C₁₀ cycloalkyl, a substitutedor unsubstituted C₂-C₁₀ alkenyl, a substituted or unsubstituted C₂-C₁₀alkynyl, or a combination comprising at least one of the foregoing, atleast one of Q and Q₁ includes a primary or secondary amino group,

X is a group represented by

wherein L is a bond, —O—, —CO—, —S—, —SO₂—, —CH₂—, —C(CH₃)₂—, —C(CF₃)₂—,or a combination comprising at least one of the foregoing,

wherein the carbonyl group and the carboxyl group may be substituted atany available carbon position except for a ring connection portion,

or a combination comprising at least one of the foregoing, or abi-functional compound that is positively charged at a first pH andnegatively charged at a second pH, wherein the compound is linked to atleast one comprising monomers represented by M0, M1, M2, M3, or acombination comprising at least one of the foregoing, below, and whereinthe bi-functional compound comprises at least one of a monomer with Aand at least one of a monomer with B,

wherein A is a group represented by —OH or —X₂—R₁₁—Y₂ where X₂ is —O—,—S—, —NR₁₂— or a combination comprising at least one of the foregoing,where R₁₂ is hydrogen, halogen, a substituted or unsubstituted C₁-C₁₀alkyl or a combination comprising at least one of the foregoing, R₁₁ isa substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, and Y₂ is —COOH,—SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing,

B is a group represented by —X₃—R₁₃—Y₃ where X₃ is —O—, —S—, —NR₁₄—. ora combination comprising at least one of the foregoing, where R₁₄ ishydrogen, halogen, and a substituted or unsubstituted C₁-C₁₀ alkyl, R₁₃is a substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, Y₃ is a grouprepresented by

where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl or a combination comprising at least oneof the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic ring, or Y₃ is a group that is represented by

and has a 4- to 8-membered alicyclic ring or a 6- to 8-membered aromaticring where R₆ and R₇ are each independently hydrogen, halogen with aproviso that R₆ is not halogen, a substituted or unsubstituted C₁-C₁₀alkyl, a substituted or unsubstituted C₃-C₁₀ cycloalkyl, a substitutedor unsubstituted C₂-C₁₀ alkenyl, a substituted or unsubstituted C₂-C₁₀alkynyl, or a combination comprising at least one of the foregoing, R₈is a substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, R₉ and R₁₀ areeach independently hydrogen, halogen, a substituted or unsubstitutedC₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀ cycloalkyl, asubstituted or unsubstituted C₂-C₁₀ alkenyl, a substituted orunsubstituted C₂-C₁₀ alkynyl, or a combination comprising at least oneof the foregoing. Unless otherwise specified, the term “substituted” asused herein means additional substituent groups including halogen,nitrile, hydroxy, carbonyl, carboxylic acid, carboxylate, C₁₋₂₀ alkyl,C₂₋₂₀ alkenyl, C₃₋₂₀ cycloalkyl, C₆₋₂₀ aryl, C₃₋₂₀ heteroalkyl, C₆₋₂₀heteroaryl or a combination comprising at least one of the foregoing.The bi-functional compound comprising A and B has a degree ofpolymerization of about 2 to about 30,000, specifically about 2 to about20,000, and more specifically about 2 to about 10,000.

In an embodiment, the bi-functional compound including monomersrepresented by M0, M1, M2, M3, or a combination thereof may includecopolymers including random copolymers, block copolymers, branchedcopolymers, dendrimers, terpolymers, or the like, or a combinationcomprising at least one of the foregoing.

In Formula I, Q or Q₁ is a group represented by —X₁—R₁—Y₁ where X₁ is—O—, —S—, —NR₂—, or a combination comprising at least one of theforegoing, where R₂ is hydrogen, halogen, and a substituted orunsubstituted C₁-C₁₀ alkyl or a combination comprising at least one ofthe foregoing. Examples of the C₁-C₁₀ alkyl group include methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, or the like, or acombination comprising at least one of the foregoing. Where R₂ issubstituted, the substituent may be halogen. Examples of —NR₂— caninclude —NH—, —N(CH₃)—, —N(CH₂CH₃)—, or the like, or a combinationcomprising at least one of the foregoing. At least one of Q and Q₁includes at least one of primary and secondary amino groups.

R₁ is a substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing. An exemplarysubstituent may be halogen, —COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻,—PO₄ ²⁻, or the like, or a combination comprising at least one of theforegoing. Examples of the substituted or unsubstituted C₁-C₁₀ alkylenemay be methylene, ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene,or the like, or a combination comprising at least one of the foregoing.An exemplary substituted or unsubstituted C₃-C₁₀ cycloalkylene may be1,1- or 1,2-cyclopropylene, 1,1-, 1,2-, or 1,3-cyclobutylene, 1,1-,1,2-, or 1,3-cyclopentylene, or the like, or a combination comprising atleast one of the foregoing. An exemplary substituted or unsubstitutedC₂-C₁₀ alkenylene may be ethenylene, 1,2- or 1,3-propenylene, or1,4-but-2-enylene, or the like, or a combination comprising at least oneof the foregoing. In addition, an exemplary substituted or unsubstitutedC₂-C₁₀ alkynylene may be ethynylene, 1,3-propynylene, or 1,4-but-(1- or2-)-ynylene, or the like, or a combination comprising at least one ofthe foregoing.

Y₁ is a group represented by

where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or the like, or a combinationcomprising at least one of the foregoing, or R₃ and R₄ may be bound toeach other to form an alicyclic or aromatic ring. Exemplary substituentgroups include halogen, a primary, secondary or tertiary amino group, orthe like, or a combination comprising at least one of the foregoing. Anexemplary alicyclic ring may include a 3- to 8-membered cycloalkyl ringor cycloalkene ring, or a combination comprising at least one of theforegoing. The aromatic ring may be a 4- to 8-membered aromatic ring. Y₁may be —NH₂, —NH(CH₃), or —NH(CH₂CH₃).

In addition, Y₁ is a group that is represented by

and has a 3- to 8-membered alicyclic ring or a 6- to 8-membered aromaticring where R₆ and R₇ are each independently hydrogen, halogen with aproviso that R₆ is not halogen, a substituted or unsubstituted C₁-C₁₀alkyl, a substituted or unsubstituted C₃-C₁₀ cycloalkyl, a substitutedor unsubstituted C₂-C₁₀ alkenyl, a substituted or unsubstituted C₂-C₁₀alkynyl, or the like, or a combination comprising at least one of theforegoing. An exemplary substituent may be halogen. Y₁ may be

or the like, or a combination comprising at least one of the foregoing.

In Formula I, Q or Q₁ may be a group represented by —X₁—R₁—Y₁ where R₁is a C₁-C₁₀ alkylene, a C₃-C₁₀ cycloalkylene, a C₂-C₁₀ alkenylene, aC₂-C₁₀ alkynylene, or the like, or a combination comprising at least oneof the foregoing, each group is substituted with at least one group of—COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing, and X₁ and Y₁ are each asdefined above.

In Formula I, Q or Q₁ may be a derivative of t

or a combination comprising at least one of the foregoing.

The compound comprising A and B is a bi-functional compound that islinked to at least one monomer represented by Formulae M0, M1, M2, M3 ora combination comprising at least one of the foregoing monomers, below,wherein the monomer comprises at least one monomer with an Asubstituent, and at least one monomer with a B substituent.

In the above formulae, A is a group represented by —OH or —X₂—R₁₁—Y₂where X₂ is —O—, —S—, —NR₁₂—, or a combination comprising at least oneof the foregoing, where R₁₂ is hydrogen, halogen, a substituted orunsubstituted C₁-C₁₀ alkyl or a combination comprising at least one ofthe foregoing. Examples of C₁-C₁₀ alkyl include methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, t-butyl, or the like, or a combinationcomprising at least one of the foregoing. Where R₁₂ is substituted, thesubstituent may be halogen. Examples of —NR₁₂— include —NH—, —N(CH₃)—,—N(CH₂CH₃)— or the like, or a combination comprising at least one of theforegoing.

R₁₁ is a substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing. The substituentmay be halogen, —COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, ora combination comprising at least one of the foregoing. Exemplarysubstituted or unsubstituted C₁-C₁₀ alkylenes may be methylene,ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, or the like, or acombination comprising at least one of the foregoing. Exemplarysubstituted or unsubstituted C₃-C₁₀ cycloalkylenes may be 1,1- or1,2-cyclopropylene, 1,1-, 1,2-, or 1,3-cyclobutylene, 1,1-, 1,2-, or1,3-cyclopentylene, or the like, or a combination comprising at leastone of the foregoing. Exemplary substituted or unsubstituted C₂-C₁₀alkenylenes may be ethenylene, 1,3-propenylene, 1,4-but-2-enylene, orthe like, or a combination comprising at least one of the foregoing. Inaddition, exemplary substituted or unsubstituted C₂-C₁₀ alkynylenes maybe ethynylene, 1,3-propynylene, or 1,4-but(-1- or -2-)ynylene.

Examples of Y₂ include —COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, and—PO₄ ²⁻.

B is a group represented by —X₃—R₁₃—Y₃ where X₃ is —O—, —S—, —NR₁₄—, ora combination comprising at least one of the foregoing, where R₁₄ ishydrogen, halogen, a substituted or unsubstituted C₁-C₁₀ alkyl, or acombination comprising at least one of the foregoing. Examples of C₁-C₁₀alkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,t-butyl, or the like, or a combination comprising at least one of theforegoing. Where R₁₄ is substituted, the substituent may be halogen.Examples of —NR₁₄— include —NH—, —N(CH₃)—, —N(CH₂CH₃)—, or the like, ora combination comprising at least one of the foregoing.

R₁₃ is a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, and a substituted or unsubstituted C₂-C₁₀ alkynyl. Where R₁₃ issubstituted, examples of the substituent include halogen, —COOH, —SO₃H,—SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combination comprising atleast one of the foregoing. The substituted or unsubstituted C₁-C₁₀alkylene may be methylene, ethylene, 1,2-propylene, 1,3-propylene,1,4-butylene or the like, or a combination comprising at least one ofthe foregoing. An exemplary substituted or unsubstituted C₃-C₁₀cycloalkylene may be 1,1- or 1,2-cyclopropylene, 1,1-, 1,2-, or1,3-cyclobutylene, or 1,1-, 1,2-, or 1,3-cyclopentylene, or the like, ora combination comprising at least one of the foregoing. An exemplarysubstituted or unsubstituted C₂-C₁₀ alkenylene may be ethenylene, 1,2-or 1-3-propenylene, 1,4-but-2-enylene, or the like, or a combinationcomprising at least one of the foregoing. In addition, an exemplarysubstituted or unsubstituted C₂-C₁₀ alkynylene may be ethynylene,1,3-propynylene, 1,4-but(-1- or -2-)ynylene, or the like, or acombination comprising at least one of the foregoing.

Y₃ is a group represented by

where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or the like, or a combinationcomprising at least one of the foregoing, or R₃ and R₄ are bound to eachother to form an alicyclic or aromatic ring. Where R₃ or R₄ issubstituted, the substituent may be halogen, a primary, secondary ortertiary amino group, or the like, or a combination comprising at leastone of the foregoing. an exemplary alicyclic ring may be a 3- to8-membered cycloalkyl or cycloalkene ring. An exemplary aromatic ringmay be a 6- to 8-membered aromatic ring. Y₃ may be —NH₂, —NH(CH₃),—NH(CH₂CH₃), or the like, or a combination comprising at least one ofthe foregoing.

Also, Y₃ is a group that is represented by

and has a 4- to 8-membered alicyclic ring or a 6- to 8-membered aromaticring where R₆ and R₇ are each independently hydrogen, halogen with aproviso that R₆ is not halogen, a substituted or unsubstituted C₁-C₁₀alkyl, a substituted or unsubstituted C₃-C₁₀ cycloalkyl, a substitutedor unsubstituted C₂-C₁₀ alkenyl, a substituted or unsubstituted C₂-C₁₀alkynyl, or a combination comprising at least one of the foregoing.Where R₆ and R₇ are themselves substituted, the substituent may behalogen. Y₃ may be

or the like, or a combination comprising at least one of the foregoing.

R₈ is a substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing. Where R₈ issubstituted, an exemplary substituent may be halogen.

R₉ and R₁₀ are each independently hydrogen, halogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing. Where R₉ and R₁₀ are substituted, an exemplarysubstituent may be halogen.

The bi-functional compound comprising A and B has a degree ofpolymerization of about 2 to about 30,000, specifically about 2 to about20,000, and more specifically about 2 to about 10,000.

The compound comprising A and B may be a group represented by —X₃—R₁₃—Y₃where R₁₃ is a C₁-C₁₀ alkylene, a C₃-C₁₀ cycloalkylene, a C₂-C₁₀alkenylene, a C₂-C₁₀ alkynylene, or a combination comprising at leastone of the foregoing, each group is substituted with at least one groupof —COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing, and X₃ and Y₃ are each thesame as defined above.

In an embodiment, for the bi-functional compound comprising monomer(s)having A and B substituents, B may be derived from an amino acidincluding

or a combination comprising at least one of the foregoing.

In the bi-functional compound according to one or more embodiments, inwhich the bi-functional compound is ionized at a first and second pH,the first pH may be about 2 to about 5, specifically greater than 2 toless than 5, more specifically about 3 to about 4.5, and still morespecifically about 3.5 to about 4.5; and the second pH may be about 7 toabout 12, specifically about 7 to about 11, more specifically about 8 toabout 11, and still more specifically about 8 to about 10.

The bi-functional compound of Formula I may be prepared by, in anembodiment, reacting a dianhydride or polyanhydride with a compoundhaving a functional group that can react with the dianhydride. In anembodiment, the compound comprises two or more functional groups.Exemplary functional groups include hydroxy, phenoxy, thiol, amino,amido, imido, and the like, and combinations of the foregoing groups. Ina specific embodiment, the compound is a nitrogen-containing compoundhaving an amino group.

Exemplary dianhydrides include 1,2,4,5-benzenetetracarboxylic aciddianhydride (pyromellitic dianhydride),3,3′,4,4′-biphenyltetracarboxylic dianhydride,2,2′,3,3′-biphenyltetracarboxylic dianhydride,2,3,3′,4′-biphenyltetracarboxylic dianhydride,1,2,4,5-benzenetetracarboxylic dianhydride,3,3′,4,4′-benzophenonetetracarboxylic dianhydride,2,2′,3,3′-benzophenonetetracarboxylic dianhydride,2,3,3′,4′-benzophenonetetracarboxylic dianhydride,bis(3,4-dicarboxyphenyl)ether dianhydride,bis(3,4′-dicarboxyphenyl)sulfone dianhydride,1,4,5,8-naphthalenetetracarboxylic dianhydride,1,2,5,6-naphthalenetetracarboxylic dianhydride,2,3,6,7-naphthalenetetracarboxylic dianhydride,2,2′-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride,cyclobutanetetracarboxylic dianhydride, methylcyclobutanetetracarboxylicdianhydride and 1,2,3,4-tetracarboxybutane dianhydride. In an exemplaryembodiment, the dianhydride may be pyromellitic dianhydride having thestructure:

In one or more embodiments, the nitrogen-containing compound has one ormore amino group, and where more than one group is present, may beheterobifunctional. Exemplary compounds having an amino functional groupmay include ethylenediamine, propylenediamine, trimethylenediamine,diethylenetriamine, triethylenetetraamine, hexamethylenediamine,heptamethylenediamine, octamethylenediamine, nonamethylenediamine,decamethylenediamine, 1,12-dodecanediamine, 1,18-octadecanediamine,3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine,4-methylnonamethylenediamine, 5-methylnonamethylenediamine,2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine,2,2-dimethylpropylenediamine, N-methyl-bis(3-aminopropyl)amine,3-methoxyhexamethylenediamine, 1,2-bis(3-aminopropoxy)ethane,bis(3-aminopropyl)sulfide, 1,4-cyclohexanediamine,bis-(4-aminocyclohexyl)methane, m-phenylenediamine, p-phenylenediamine,2,4-diaminotoluene, 2,6-diaminotoluene, m-xylylenediamine,p-xylylenediamine, 2-methyl-4,6-diethyl-1,3-phenylene-diamine,5-methyl-4,6-diethyl-1,3-phenylene-diamine, benzidine, tryptamine,4-aminomethylpyridine, 1-(2-aminoethyl)imidazole,1-(3-aminopropyl)imidazole, 1-(4-aminobutyl)imidazole,1-(5-aminopentyl)imidazole, 1-(6-aminohexyl)imidazole,3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 1,5-diaminonaphthalene,bis(4-aminophenyl)methane,bis(2-chloro-4-amino-3,5-diethylphenyl)methane,bis(4-aminophenyl)propane, 2,4-bis(b-amino-t-butyl) toluene,bis(p-b-amino-t-butylphenyl)ether, bis(p-b-methyl-o-aminophenyl)benzene,bis(p-b-methyl-o-aminopentyl)benzene, 1,3-diamino-4-isopropylbenzene,bis(4-aminophenyl) sulfide, bis(4-aminophenyl)sulfone,bis(4-aminophenyl)ether, 1,3-bis(3-aminopropyl)tetramethyldisiloxane.Amine-based amino acids may also be used, such as for example histidine,lysine, arginine, proline, and tryptophan. Polyamines, including linear,branched, hyperbranched, or dendrimeric polyamines, may also be used.Mixtures comprising at least one of these compounds may also be present.In an exemplary embodiment, the compound is ethylene diamine,4-aminomethylpyridine, 1-(3-aminopropyl)imidazole), histidine, lysine,arginine, or a combination comprising at least one of the foregoing.

The bi-functional compound comprising A and B may be prepared by, forexample, hydrolyzing a polyanhydride to form a carboxylic acid group,followed by activation of a resulting carboxylic acid group by reactingthe carboxylic acid group with a material such as, N-hydroxysuccinimide(“NHS”) in the presence of a dehydrating agent such asdicyclohexylcarbodiimide or1,[3-(dimethylamino)propyl]-3-ethylcarbodiimide and an organic aminebase (e.g., triethylamine) to form an activated intermediate compoundhaving an ester bond (where in the case of N-hydroxysuccinimide, theactivated intermediate compound is an NHS ester), and thencoupling-reacting the so-activated carboxyl group with compound A (forexample, H₂O) or compound B (for example, 1-(3-aminopropyl)imidazole).In another embodiment, after hydrolyzing the polyanhydride, thecoupling-reacting may be carried out directly between the hydrolyzedpolyanhydride and compound A or B in the presence of a dehydrating agentsuch as for example dicyclohexylcarbodiimide or1,[3-(dimethylamino)propyl]-3-ethylcarbodiimide, and a catalyst (e.g.,N,N-dimethylaminopyridine or 4-pyrrolidinopyridine).

Exemplary polyanhydrides include, for example, poly(ethylene-alt-maleicanhydride, styrene-alt-maleic anhydride, (styrene-alt-maleicanhydride)-co-styrene diblock copolymer, styrene-acrylate-maleicanhydride terpolymers, and the like, or a combination comprising atleast one of the foregoing. In an exemplary embodiment, thepolyanhydride is poly(ethylene-alt-maleic anhydride). It should be notedthat these polyanhydrides are exemplary and should not be considered aslimited thereto.

In an embodiment, the polyanhydride has a weight average molecularweight (Mw) of 100,000 to 500,000, specifically 125,000 to 475,000, morespecifically 150,000 to 450,000, and still more specifically 150,000 to400,000.

Alternatively, the compound comprising A and B may be prepared bydirectly reacting a polyanhydride (for example, poly(ethylene-alt-maleicanhydride, having an Mw of 100,000 to 500,000) with a reactantcomprising A (for example, H₂O) or a reactant comprising B (for example,1-(3-aminopropyl)imidazole). In this regard, a net charge of thecompound comprising A and B may be adjusted by having A or B containedin the compound at an appropriate ratio in the reaction.

In an embodiment, a solid support on which a bi-functional compound isimmobilized can therefore be prepared by sequentially reacting asubstrate, a surface treatment agent, a dianhydride or polyanhydride,and a nitrogen-containing compound, wherein the bi-functional compoundimmobilized on the substrate is positively charged at a first pH andnegatively charged at a second pH. The resulting reaction product is asolid support having a bi-functional compound immobilized thereon.

One or more embodiments include a solid support in which the compounddescribed above is immobilized on a surface thereof. In an embodiment,the solid support comprises a substrate and the bi-functional compound.

The substrate of the solid support on which the compound is immobilizedmay have the form of, for example, a planar plate, a multilayeredstructure, a non-planar structure such as sphere, bead, sieve or pillar,or a surface in a microchannel, but is not limited to these. Where thesurface of each of these substrates has additional features or texturesfor increasing surface area, the features may include pits, holes,posts, grooves, linear or nonlinear lines and spaces, and the like, andcombinations of the foregoing. In an embodiment, the solid support mayhave a shape of the surface of the microchannel in a microfluidicdevice.

The substrate of the solid support on which the compound is to beimmobilized may be glass, magnetic beads, silica, fused silica,polyethylene, polypropylene, polycarbonate, polyester, polyimide, slideglass, silicon, TiO₂, Al₂O₃, SiN_(X), TiN_(X), sapphire, metals such assteel, aluminum, titanium, tantalum, silver, gold, platinum, substratessuch as SiO₂ or silicon coated with one of these metals, or the like, ora combination comprising at least one of the foregoing. The foregoingembodiments should be considered exemplary and should not be consideredas limited thereto.

The solid support may be prepared by activating a terminal portion of achain of the compound with an activator comprising an active group suchas an aldehyde, an anhydride including mixed anhydride, an acid halide,or an activated ester group (e.g., an NHS ester), and coupling theactivated compound with a solid support previously treated to have afunctional group, such as an amino group, on the surface. The activationof the compound and the solid support may be performed using any knownmethod. For example, the compound may be activated by oxidizing aterminal group of the compound, or by coupling the compound with anester compound, an aldehyde, an acid halide, or an anhydride tointroduce an active group into the compound.

The solid support may be treated with a surface-treating agent thataffixes to the surface of the solid support, and provides a freenitrogen-containing group to allow attachment of the activatedcarboxylic acid group. In an embodiment, the surface treating agent isheterobifunctional and provides at one end a nitrogen-containingfunctional group, such as an amine, and at the other end, a reactivegroup that can react to form a covalent bond to the surface of the solidsupport. In another embodiment, the solid support may be treated with asurface treating agent having an isocyanate or isothiocyanate-containinggroup, and at the other end, a reactive group that can react to form acovalent bond to the surface of the solid support. In an embodiment,where an isocyanate or isothiocyanate is used, the bifunctional compoundimmobilized on the treated surface of the solid support may be anamine-containing polymer, or a phenol-containing polymer, whereimmobilization of such polymers may be accomplished via a urea orurethane link. In another embodiment, it will be appreciated that anisocyanate or isothiocyanate surface-treating agent may be furthertreated with, for example, ammonia, or a polyfunctional amine to provideadditional amine or other functional groups for reaction with theactivated compound.

Exemplary surface treating agents include, but are not limited to,aminosilanes such as 3-aminopropylsilane, 3-aminopropylmethoxysilane,3-aminopropyldimethoxysilane, 3-aminopropyldimethylsilane,3-aminopropyl(methoxydimethylsilane), 3-aminopropyl(trimethoxysilane),3-aminopropyl(triethoxysilane), 3-aminopropyl(triisopropoxysilane),3-aminopropyl(tributoxysilane), 3-isocyanatopropylsilane,3-isocyanatopropyl(trimethoxysilane), 3-isothiocyanatopropylsilane,3-isothiocyanatopropyl(trimethoxysilane), or the like, or a combinationcomprising at least one of the foregoing.

The solid support may be activated by coating a surface of the solidsupport with an active material such as an aminosilane by a conventionalcoating technique (e.g., dip coating, spin coating, and the like, butnot limited to these). Alternatively, the solid support on which thecompound is immobilized may be prepared by coating an activatedsubstrate with the polyanhydride as described above (for example,poly(ethylene-alt-maleic anhydride having an Mw of 100,000-500,000),hydrolyzing an anhydride moiety of the polyanhydride coated on thesubstrate to expose a carboxylic acid group, reacting the carboxylicacid group with N-hydroxysuccinimide in the presence of dicyclohexanecarbodiimide or 1,[3-(dimethylamino)propyl]-3-ethylcarbodiimide in thepresence of an amine base to activate the carboxyl group by forming theNHS ester, and then coupling-reacting the activated carboxylic acidgroup with a reactant comprising A (for example, H₂O) or the reactantcomprising B (for example, 1-(3-aminopropyl)imidazole).

One or more embodiments include a method of isolating a nucleic acid bywith the compound and the solid support on which the compound isimmobilized, the method including: contacting the compound or the solidsupport on which the compound is immobilized with a sample comprising anucleic acid at a first pH; and exposing the compound with the nucleicacid bound thereto to a solution with a second pH that is higher thanthe first pH, to release the nucleic acid.

In an embodiment, the method of isolating the nucleic acid includescontacting the compound or the solid support on which the compound isimmobilized with the sample comprising the nucleic acid at the first pH.The sample may be a biological or non-biological sample comprising anucleic acid, for example, blood lysate, cell lysate, polymerase chainreaction (“FOR”) products, or a combination comprising at least one ofthe foregoing. The compound and/or the solid support on which thecompound is immobilized are as described hereinabove. In an embodiment,the first pH may be about 2 to about 5, specifically greater than orequal to 2 to less than 5, more specifically about 3 to about 4.5, andstill more specifically about 3.5 to about 4.5.

In an embodiment, the method of isolating the nucleic acid includesexposing the compound, for example, the compound on the solid support,and having the nucleic acid bound thereto, to the solution having asecond pH higher than the first pH, to release the nucleic acid. Thesecond pH may be about 7 to about 12, specifically about 7 to about 11,more specifically about 8 to about 11, and still more specifically about8 to about 10. A solution for eluting the nucleic acid may include wateror an appropriate aqueous buffer. An example of an aqueous buffer is atris-hydroxymethyl aminomethane-ethylene diamine tetraacetic acid buffer(Tris-EDTA buffer). Exposing of the compound to the buffer may beperformed at room temperature or at a temperature higher than roomtemperature, for example, at a temperature of 50 to 95° C.

In an embodiment, where an aqueous buffer solution is used for exposingthe compound, the total buffer concentration is 0.001 to 10M,specifically 0.01 to 5 M, and more specifically 0.1 to 2 M.

An exemplary method of forming a surface immobilized compound on a solidsupport, according to an embodiment, is shown below. In the exemplarymethod shown in Reaction Scheme 1:

a treated surface (1) (e.g., silicon dioxide) previously treated with asurface treating agent (e.g., 3-aminopropyltriethoxysilane), is thenreacted with a dianhydride (e.g., pyromellitic dianhydride (2)) to formanhydride intermediate (3). Intermediate (3) is then hydrolyzed, and theresulting free acid groups reacted with a diamine (e.g.,4-aminomethylpyridine) in the presence of a dehydrating agent (acarbodiimide, such as 1,[3-(dimethylamino)propyl]-3-ethylcarbodiimide)to form the bifunctional material (4).

Another exemplary method of forming a surface immobilized compound on asolid support, according to an embodiment, is shown below. In theexemplary method shown in Reaction Scheme 2:

a treated surface (5) (e.g., silicon dioxide) previously treated with asurface treating agent (e.g., 3-aminopropyltriethoxysilane), is thenreacted with a polymeric anhydride (e.g., poly(ethylene-alt-maleicanhydride (6)) to form anhydride intermediate (7). Intermediate (7) isthen hydrolyzed, and the resulting free acid groups reacted with adiamine (e.g., ethylene diamine as shown) in the presence of adehydrating agent (a carbodiimide, such as1,[3-(dimethylamino)propyl]-3-ethylcarbodiimide) to form thebifunctional material (8).

It will be appreciated that the above exemplary processes are forillustrative purposes and should not be construed as limiting thereto.

Hereinafter, one or more embodiments will be described in detail withreference to the following examples. However, these examples areincluded as exemplary are not intended to limit the purpose and scope ofthe invention.

Example 1 Synthesis of Bi-Functional Material Positively Charged at aFirst pH and Negatively Charged at Second pH on Silicon Substrate, andAnalysis Thereof

(1) Preparation of Bi-Functional Material that is Positively Charged atFirst pH and Negatively Charged at Second pH.

A silicon wafer substrate (25 mm×25 mm, with silicon dioxide depositedthereon to a thickness of about 1,000 angstroms) is immersed in asolution of 100 mM 3-aminopropyltriethoxysilane in ethanol, andincubated at room temperature for about 1 hour. The silicon substrate sotreated was washed using anhydrous ethano to provide a silicon substratewith amino groups introduced on its surface. The silicon substratehaving the amino groups so introduced is next immersed in a solution of200 mM poly(ethylene-alt-maleic anhydride) having an Mw of 100,000 to500,000, and a degree of polymerization n=900 to 4,000) based on arepeating unit of ethylene-maleic anhydride in N-methyl-2-pyrrolidone(“NMP”) and incubated at room temperature for 1 hour.Poly(ethylene-alt-maleic anhydride thus reacts with the amino groupspresent on the surface of the silicon substrate, and are immobilized onthe silicon substrate. Subsequently, samples of the silicon substrate sotreated is alternately washed with N-methyl-2-pyrrolidone (NMP) andethanol, and dried.

Samples of the dried silicon substrate are then immersed in either a.) asolution of 400 mM ethylenediamine and 600 mM water in NMP, or b.) asolution of 400 mM 4-aminomethylpyridine and 600 mM water in NMP, and isincubated at room temperature in each solution for 1 hour. Thereafter,the silicon substrates are washed with ethanol and dried. As a result,two types of silicon substrate, each of which was coated with abi-functional material (sample (a), having ethylene diamine and hydroxygroups; and sample (b), having 4-aminomethylpyridine and hydroxygroups), are prepared.

(2) Analysis of the Silicon Substrate Coated with the Bi-FunctionalMaterial Prepared from the Solution of 400 mM of Ethylenediamine and 600mM of Water in NMP (Sample (a).

X-ray photoelectron spectroscopy (“XPS”) analysis was performed on thesilicon substrate coated with the bi-functional material prepared fromthe solution of 400 mM of ethylenediamine and 600 mM of water in NMP(sample (a), as described in (1) above) in order to determine thepresence of functional groups on the surface of the silicon substrate. APhysical Electronics Quantum2000 microprobe with a monochromated A1KαX-ray source (hυ=1486.6 eV) was used as the XPS device. Functionalgroups corresponding to ethylene diamine and hydroxy were found to existon the surface of the silicon substrate.

In the XPS spectra obtained from the analysis, the nitrogen 1 s orbitalpeak appearing at 400 eV, and representing the binding energy for aprimary amino group, showed a greater intensity in the XPS spectra forthe silicon substrate coated with the bi-functional material than wasseen in the XPS spectra on the silicon substrate coated only with3-aminopropyltriethoxysilane. This result shows that the bi-functionalmaterial has a plurality of surface-bound primary amino groups asprovided by the above method.

In addition, the magnitude of the carbon 1 s orbital peak appears at 285eV, at a binding energy representing carbon that is directly bound to aprimary amino group. The observed intensity is significantly greater inXPS spectra for the silicon substrate coated with the bi-functionalmaterial than for the XPS spectra of the silicon substrate coated with3-aminopropyltriethoxysilane. This result shows that the bi-functionalmaterial has carbon that is directly bound to a plurality of primaryamino groups.

In addition, a carbon 1 s orbital peak also appears at 288 eV, a bindingenergy representing a carbonyl (C═O) group, has a greater intensity inXPS spectra for the silicon substrate coated with the bi-functionalmaterial, than seen in the XPS spectra for the silicon substrate coatedwith 3-aminopropyltriethoxysilane. This result thus further shows thatthe bi-functional material has an associated carbonyl group.

From the results above, it is thus qualitatively confirmed that thebi-functional material, which has an amino group and a carbonyl group,including a carbonyl group connected to a hydroxy (—OH) group, is coatedon the silicon substrate by the above method.

(3) Analysis of the Silicon Substrate Coated with the Bi-FunctionalMaterial Prepared from the Solution of 400 mM of 4-Aminomethylpyridineand 600 mM of Water in NMP (Sample (b)).

Time-of-flight secondary ion mass spectrometry (“TOF-SIMS”) analysis isperformed on the silicon substrate coated with the bi-functionalmaterial prepared from the solution of 400 mM of 4-aminomethylpyridineand 600 mM of water in NMP (sample b, as described in Experiment (1)above), to analyze a surface of the silicon substrate. A TOF-SIMS Vapparatus (available from ION-TOF GmbH, Germany) emitting 15 kV Garadiation (average current: 1 pA, pulse time: 200 μs) was used as aTOF-SIMS apparatus.

In the data, a peak (m/z=79) representing pyridine is observed, showingthat the surface of the silicon substrate is coated with a materialhaving pyridine. In addition, by XPS analysis as described above, it canalso be shown that a carbonyl group is present on the surface of thesilicon substrate, and the carbonyl group includes a carbonyl grouphaving a hydroxy (—OH) group.

Thus, the bi-functional material, having both a pyridine group and acarbonyl group, where the carbonyl group includes a carbonyl grouphaving an —OH group, is coated on the silicon substrate.

Example 2 Isolation of Genome DNA by Using Bi-Functional Material thatis Positively Charged at First pH and Negatively Charged at Second pH

(1) Preparation of Bi-Functional Material that is Positively Charged atFirst pH and Negatively Charged at Second pH.

Poly(ethylene-alt-maleic anhydride) (Mw 100,000 to 500,000; degree ofpolymerization n=900 to 4,000 is immobilized on a magnetic bead coatedwith an amino group (available from Invitrogen, under the trade name ofDyanl AS DYNABEADS® M-270 Amine, 2×10⁹ beads/ml, with a diameter of 2.8μm), and the magnetic bead is reacted with 1-(3-aminopropyl)imidazole toprepare a material having a carboxyl group and an imidazole group,capable of having a positive charge at a first pH of 2 to 5, andnegative charge at a second pH of 7 to 12.

First, the magnetic bead coated with the amino group is immersed in asolution of 200 mM the above-mentioned poly(ethylene-alt-maleicanhydride) based on the repeating unit of ethylene-maleic anhydride, inN-methyl-2-pyrrolidone (NMP) is incubated at room temperature for 1hour. Next, poly(ethylene-alt-maleic anhydride is reacted with the aminogroup on the magnetic bead and thereby immobilized on the magnetic bead.After this reaction, the magnetic bead is washed with ethanol and dried.

Next, the magnetic bead with the polyanhydride (poly(ethylene-alt-maleicanhydride) immobilized thereon was added to a solution of 400 mM of1-(3-aminopropyl)imidazole and 600 mM of water in N-methyl-2-pyrrolidone(NMP) and incubated at room temperature for 1 hour. Then, the magneticbead was washed with ethanol. In this way, a material with a carboxylgroup and an imidazole group, is prepared. The prepared material waswashed with ethanol and dried.

The material so prepared is a bi-functional compound that is bound to atleast one monomer monomers represented by formulae M0, M1, M2, and M3below and comprises at least one of a monomer with A and at least one ofa monomer with B,

wherein A is —OH, B is a compound represented by

R₈ is ethyl, and R₉ and R₁₀ are each independently hydrogen. It is notedthat for present purposes, the structure of monomer units of M1 and M2are interchangeable.

Characterization of the magnetic bead was performed as described inExample 1 above, by XPS and TOF-SIMS analysis to confirm the surfacecomposition of the magnetic bead having the bi-functional compoundimmobilized thereon. Thus, in the XPS analysis, it is seen that theprepared compound has a carbonyl group, and the carbonyl group includesa carbonyl group having a hydroxyl (—OH). In addition, in the TOF-SIMSanalysis, it is seen that the bi-functional compound has an imidazolylgroup.

(2) Isolation of Genome DNA by Using Bi-Functional Material

E. coli genome DNA was isolated using the magnetic bead with thebi-functional material prepared in (1) above immobilized thereon.

E. coli in phosphate buffered saline solution (“PBS”) (0.1 OD₆₀₀) wasthermally lysed by heating twice at each of 95° C. for 5 minutes and 0°C. for 1 minute.

Next, each of 10 μl (2×10⁷ beads), 30 μl (6×10⁷ beads), and 50 μl (1×10⁸beads) of a solution of the magnetic bead with the bi-functionalmaterial prepared in (1) above immobilized thereon (2×10⁹ beads/ml, indistilled water) was taken, and each magnetic bead solution wasexchanged with a binding buffer, 100 μl of a 100 mM sodium acetatebuffer (pH 4). 100 μl of the magnetic bead solution and 50 μl of E. colilysate were mixed together, and vortexed for 2 minutes. The magneticbeads were separated from the mixed solution with a magnet. Theconcentration of DNA in the solution from which the magnetic beads wereremoved was measured using a NANODROP™ ND1000 apparatus (obtained fromThermo Scientific).

The separated magnetic beads were suspended in a 10 mM Tris-HCl buffer,pH 7, and vortexed for 1 minute. The magnetic beads were separated fromthe solution by using a magnet, and washed.

The washed magnetic beads were suspended in a 100 mM Tris-HCl buffer, pH9, and incubated at 80° C. for 4 minutes while vortexing was performedfor 5 seconds every 30 seconds to elute a nucleic acid from the magneticbeads. Then, the magnetic beads were removed from the solution by usinga magnet to obtain a solution comprising an isolated genome DNA. Theamount of nucleic acid in the obtained solution was quantified using aNANODROP™ ND1000 apparatus.

Table 1 shows a binding efficiency of the nucleic acid in E. coli lysateto the magnetic beads with the bi-functional material prepared in (1)above immobilized thereon and an elution efficiency of the nucleic acidfrom the magnetic beads.

TABLE 1 Bead number Binding efficiency (%) Elution efficiency (%) 2 ×10⁷ 88.4 ± 1.6 99.2 ± 5.6 6 × 10⁷ 93.8 ± 0.9 95.8 ± 6.8 1 × 10⁸ 99.2 ±1.3 80.4 ± 3.3

In Table 1, the binding efficiency and the elution efficiency arerespectively defined as the DNA binding amount/amount of DNA existing inlysate solution×100, and the DNA elution amount/DNA binding amount×100.

(3) Isolation of Genome DNA by Using Bi-Functional Material: Effect ofBinding Buffer pH

A 100 mM sodium acetate buffer used as a binding buffer is varied tohave a pH of 3, 4, or 5, and elution is performed at each pH byincubating the magnetic beads having the bound DNA in buffer at 65° C.for 2 minutes. The number of magnetic beads used was 6×10⁷ per ml;otherwise, the experimental processes were performed in the same manneras in (2) above.

Table 2 shows, according to a change in pH, the binding efficiency ofthe nucleic acid in E. coli lysate to the magnetic beads with thebi-functional material prepared in (1) above immobilized thereon,elution efficiency of the nucleic acid from the magnetic beads, andyield.

TABLE 2 Binding Elution Binding buffer pH efficiency (%) efficiency (%)Yield (%) 3 99.0 69.0 68.3 4 95.5 83.2 79.5 5 34.0 88.0 29.9

In Table 2, the binding efficiency and the elution efficiency are thesame as defined in those of Table 1, and the yield (%) is defined asbinding efficiency×elution efficiency.

From the results of Table 2, it was confirmed that at pH 5 or less, thelower the pH, the greater the binding efficiency, and at pH 5 or less,the higher the pH, the greater the elution efficiency. As a result, asthe pH increases from 3 to 5, the yield was increased and thendecreased.

(4) Effect of Elution Buffer pH

The effect of the pH of the elution buffer was determined in the samemanner as in (2) above, except that a 100 mM sodium acetate buffer witha pH 4 was used as a binding buffer, and the pH of the elution bufferwas varied as described below. The number of magnetic beads used was6×10⁷ per ml.

The elution buffer used was either a 100 mM Tris-HCl solution at pH 7, a100 mM Tris-HCl solution at pH9, or a 100 mM sodium carbonate solutionat pH 11.

Table 3 shows how change in pH affects elution efficiency. The elutionefficiency is as defined above.

TABLE 3 Elution pH 7 8 11 Elution efficiency (%) 70.5 83.2 91.2

From the results of Table 3, it can be seen that elution is efficientlyperformed at pH 7 or more. After a supplementary experiment wasperformed, it was demonstrated that elution was efficiently performedeven at pH 12.

Example 3 Isolation of Genome DNA by Using Material that is PositivelyCharged at First pH and Negatively Charged at Second pH

Bi-functional compounds having histidine, lysine and arginine moietieswere prepared, and genome DNA was isolated using these bi-functionalcompounds.

(1) Preparation of Bi-Functional Compound Having a Histidine Moiety

Experimental Group 1: silica bead on which a bi-functional materialhaving a pyridyl group is immobilized. A silica bead having an averagediameter of about 14 μm is immersed in a solution of 100 mM of3-aminopropyltriethoxysilane in ethanol and incubated at roomtemperature for 1 hour. Then, the silica bead is washed using anhydrousethanol to prepare a silica bead to which an amino group was introduced.Thereafter, the thus-obtained silica bead with the amino group on itssurface is immersed in a solution of 200 mM of poly(ethylene-alt-maleicanhydride having an average molecular weight of 100,000 to 500,000, anda degree of polymerization n=900 to 4,000, based on a repeating unit ofethylene-maleic anhydride, in N-methyl-2-pyrrolidone (NMP) and incubatedat room temperature for 1 hour. After the incubating, the silica bead isalternately washed using pure N-methyl-2-pyrrolidone (NMP) and ethanoland then dried. Thus, a silica bead on which poly(ethylene-alt-maleicanhydride is immobilized, is obtained.

Then, the silica bead so obtained is immersed in a solution of 400 mM of4-aminomethylpyridine and 600 mM of water in NMP and incubated at roomtemperature for 1 hour. The silica bead is then washed with ethanol anddried.

Experimental Group 2: silica bead on which a bi-functional materialhaving a histidine moiety is immobilized. A silica bead with abi-functional material having a histidine moiety immobilized thereon isprepared as follows. First, the prepared silica bead on whichpoly(ethylene-alt-maleic anhydride) are immobilized is immersed in asolution of 100 mM 4-morpholineethanesulfonic acid (“MES”) at pH 6 indistilled water and incubated for 4 hours to hydrolyze thepolyanhydride, then dried. Then, the dried silica bead are immersed in asolution of 100 mM of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimidehydrochloride (“EDC”) and 200 mM of N-hydroxysuccinimide (NHS) inethanol with 10% MES (v/v) included, and incubated at room temperaturefor 30 minutes. Then, the silica bead was washed using water and ethanolin this order and dried. In this way, a silica bead having an activatedcarbonyl group was obtained. The dried silica bead is then immersed in asolution of 200 mM of histidine in 100 mM phosphate buffered saline(PBS), pH 7.4 and incubated at room temperature for 2 hours. Then, thesilica bead is washed with water and ethanol in this order and dried.

The compound synthesized on the silica bead, as Experimental Group 2, isa bi-functional compound that is bound to at least one monomer monomersrepresented by Formulae M0, M1, M2, and M3 below and comprises at leastone of a monomer with A and at least one of a monomer with B,

wherein A is —OH,

B is

R₈ is ethyl, and R₉ and R₁₀ are each independently hydrogen. It is notedthat for present purposes, the structure of monomer units of M1 and M2are interchangeable.

The presence of a carbonyl group including the carbonyl group that isdirectly bound to —OH, and the histidine moiety on the silica bead areconfirmed using XPS and TOF-SIMS analyses.

(2) Isolation of Genome DNA by Using the Prepared Silica Bead

Genome DNA was isolated using the silica beads prepared in (1) above asExperimental Groups 1 (4-aminomethylpyridine) and 2 (histidine).

First, 0.01 g of each of the silica beads of Experimental Groups 1 and2, 70 μl of 100 mM sodium acetate, pH 3 (binding solution), and 140 μlof purified E. coli genome DNA (28 ng/μl in distilled water) is mixedwhile being tumbled for 3 minutes. The mixture is rotated at 1000 rpmfor 1 minute and then a supernatant removed from the mixture. 210 μl of10 mM Tris-HCl at pH 7.4 as a washing buffer is added to the separatedsilica bead, and the resultant is mixed while being vortexed for 1minute. The mixture is rotated at 1,000 rpm for 1 minute, andsupernatant is removed. 210 μl of a Tris-EDTA (“TE”) buffer (100 mMTris-HCl-EDTA at pH 8.2) as an elution buffer is added to the separatedsilica beads and the resultant incubated at 70° C. for 3 minutes.

The concentration of DNA in each step is measured using a NANODROP™ND1000 apparatus, to determine binding efficiency, elution efficiency,and yield.

TABLE 4 Binding Elution Silica Bead Efficiency (%) Efficiency (%) Yield(%) Experimental Group 1a^(a) 100 84.5 84.5 Experimental Group 1b^(a)98.3 80.1 78.7 Experimental Group 2a^(a) 77.5 82.9 64.2 ExperimentalGroup 2b^(a) 77.9 85.7 66.8 ^(a)Note: sub-designations a and b refer torepeat runs.

Each experiment was repeated twice. As seen in the data in Table 4, theyield of Experimental Group 1 (the 4-aminomethylpyridine-modified bead)is significantly greater, varying from 11.9% to 20.3% to 11.9% greaterthan the yield of Experimental Group 2 (the histidine-modified bead).

A second set of experiment was performed in the same manner as in theexperiment described above, but using 0.02 g of the silica bead fromExperimental Group 2 and as a binding solution, 200 mM sodium acetate atpH 3. Table 5 shows results of DNA isolation when the amount of silicabead and the concentration of binding solution were increased.

TABLE 5 Binding Elution Silica Bead Efficiency (%) Efficiency (%) Yield(%) Experimental Group 2c^(b) 93.3 81.9 76.4 Experimental Group 2d^(b)85 82.7 70.3 ^(b)Note: sub-designations c and d are repeat runs.

As shown in Table 5, the yield of Experimental Groups 2c and 2d varyfrom about 3.5 to 12.2% greater than Experimental Groups 2a and 2b inTable 4.

(3) Preparation of Silica Bead with Bi-Functional Compound Having aLysine or Arginine Moiety Immobilized Thereon and Isolation of GenomeDNA Using the Same.

Silica bead on which a bi-functional compound having a lysine orarginine moiety was immobilized (respectively referred to as silicabeads of Experimental Groups 3 and 4) was prepared according to theprocedure described in Example (3), (1) above using lysine or arginineinstead of histidine. The bi-functional compound is then evaluated forgenome DNA binding and purification also as above, and is isolated inthe same manner as in (2) above from the prepared silica beads for eachof Experimental Groups 3 and 4.

TABLE 6 Binding Elution Silica Bead Efficiency (%) Efficiency (%) Yield(%) Experimental Group 3 84.3 77.3 65.2 Experimental Group 4 86.1 79.168.1

As seen in the data in Table 6 above, the yield for lysine (65.2%,Experimental Group 3) and arginine (68.1%, Experimental Group 4) isabout the same as that observed for histidine (64.2% and 66.8% forExperimental Groups 2a and 2b, respectively; see Table 4). From theabove, it can be seen that the highest overall yield is obtained fromthe 4-aminomethylpyridine modified beads, irrespective of buffer pH.

Thus, according to the one or more of the above embodiments, a nucleicacid can be efficiently isolated using a bi-functional material and asolid support with the bi-functional material immobilized thereon.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

1. A bi-functional compound that is positively charged at a first pH andnegatively charged at a second pH, the bi-functional compoundrepresented by Formula I below:Q-X-Q₁  (Formula I) wherein Q or Q₁ is a group represented by —X₁—R₁—Y₁where X₁ is —O—, —S—, or —NR₂— or a combination comprising at least oneof the foregoing, where R₂ is hydrogen, halogen, and a substituted orunsubstituted C₁-C₁₀ alkyl, R₁ is a substituted or unsubstituted C₁-C₁₀alkylene, a substituted or unsubstituted C₃-C₁₀ cycloalkylene, asubstituted or unsubstituted C₂-C₁₀ alkenylene, a substituted orunsubstituted C₂-C₁₀ alkynylene, r a combination comprising at least oneof the foregoing, Y₁ is a group represented by

 where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic group, or Y₁ is a group that is represented by

 and has a 4- to 8-membered alicyclic ring or a 6- to 8-memberedaromatic ring where R₆ and R₇ are each independently hydrogen, halogen,a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, at least one of Q and Q₁ has a primary or secondary aminogroup, X is a compound represented by

 wherein L is a bond, —O—, —CO—, —S—, —SO₂—, —CH₂—, —C(CH₃)₂—,—C(CF₃)₂—, or a combination comprising at least one of the foregoing,

 wherein the carbonyl group and the carboxyl group are substituted atany available carbon position except for a ring connection portion,

 or a combination comprising at least one of the foregoing, abi-functional compound that is positively charged at a first pH andnegatively charged at a second pH, wherein the bi-functional compound islinked to at least one monomer comprising monomers represented by M0,M1, M2, M3, or a combination comprising at least one of the foregoing,below, and wherein the bi-functional compound comprises at least one ofa monomer with A and at least one of a monomer with B,

wherein A is a group represented by —OH or —X₂—R₁₁—Y₂ where X₂ is O—,—S—, —NR₁₂—, or a combination comprising at least one of the foregoing,where R₁₂ is hydrogen, halogen, a substituted or unsubstituted C₁-C₁₀alkyl, or a combination comprising at least one of the foregoing, R₁₁ isa substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, and Y₂ is —COOH,—SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing, B is a group represented by—X₃—R₁₃—Y₃ where X₃ is O—, —S—, —NR₁₄—, or a combination comprising atleast one of the foregoing, where R₁₄ is hydrogen, halogen, and asubstituted or unsubstituted C₁-C₁₀ alkyl, R₁₃ is a substituted orunsubstituted C₁-C₁₀ alkylene, a substituted or unsubstituted C₃-C₁₀cycloalkylene, a substituted or unsubstituted C₂-C₁₀ alkenylene, and asubstituted or unsubstituted C₂-C₁₀ alkynylene, or a combinationcomprising at least one of the foregoing, Y₃ is a group represented by

 where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic ring, or Y₃ is a group that is represented by

 and has a 4- to 8-membered alicyclic ring or a 6- to 8-memberedaromatic ring where R₆ and R₇ are each independently hydrogen, halogen,a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, R₈ is a substituted or unsubstituted C₁-C₁₀ alkylene, asubstituted or unsubstituted C₃-C₁₀ cycloalkylene, a substituted orunsubstituted C₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀alkynylene, or a combination comprising at least one of the foregoing,R₉ and R₁₀ are each independently hydrogen, halogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, wherein the bi-functional compound comprising Aand B has a polymerization degree of about 2 to about 30,000.
 2. Thebi-functional compound of claim 1, wherein Q or Q₁ is a grouprepresented by —X₁—R₁—Y₁ where R₁ is a C₁-C₁₀ alkylene, a C₃-C₁₀cycloalkylene, a C₂-C₁₀ alkenylene, a C₂-C₁₀ alkynylene, or acombination comprising at least one of the foregoing, each of the groupbeing substituted with at least one group of —COOH, —SO₃H, —SO₂H, —SOH,—H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combination comprising at least one ofthe foregoing, and B is a group represented by —X₃—R₁₃—Y₃ where R₁₃ is aC₁-C₁₀ alkylene, a C₃-C₁₀ cycloalkylene, a C₂-C₁₀ alkenylene, a C₂-C₁₀alkynylene, or a combination comprising at least one of the foregoing,each of the group being substituted with at least one group of —COOH,—SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing.
 3. The bi-functional compoundof claim 1, wherein the first pH is about 2 to about 5, and the secondpH is about 7 to about
 12. 4. The bi-functional compound of claim 1,wherein Q or Q₁ is

or a combination comprising at least one of the foregoing, and B

or a combination comprising at least one of the foregoing.
 5. A solidsupport on which a bi-functional compound is immobilized, comprising: asubstrate, and a bi-functional compound immobilized on the substrate,the bi-functional compound being positively charged at a first pH andnegatively charged at a second pH, and represented by Formula I below:Q-X-Q₁  (Formula I) wherein Q or Q₁ is a group represented by —X₁—R₁—Y₁where X₁ is —O—, —S—, or —NR₂— or a combination comprising at least oneof the foregoing, where R₂ is hydrogen, halogen, and a substituted orunsubstituted C₁-C₁₀ alkyl, R₁ is a substituted or unsubstituted C₁-C₁₀alkylene, a substituted or unsubstituted C₃-C₁₀ cycloalkylene, asubstituted or unsubstituted C₂-C₁₀ alkenylene, a substituted orunsubstituted C₂-C₁₀ alkynylene, r a combination comprising at least oneof the foregoing, Y₁ is a group represented by

 where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic group, or Y₁ is a group that is represented by

 and has a 4- to 8-membered alicyclic ring or a 6- to 8-memberedaromatic ring where R₆ and R₇ are each independently hydrogen, halogen,a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, at least one of Q and Q₁ has a primary or secondary aminogroup, X is a compound represented by

 wherein L is a bond, —O—, —CO—, —S—, —SO₂—, —CH₂—, —C(CH₃)₂—,—C(CF₃)₂—, or a combination comprising at least one of the foregoing,

 wherein the carbonyl group and the carboxyl group are substituted atany available carbon position except for a ring connection portion,

 or a combination comprising at least one of the foregoing, or abi-functional compound that is positively charged at a first pH andnegatively charged at a second pH, wherein the bi-functional compound islinked to at least one monomer comprising monomers represented by M0,M1, M2, M3, or a combination comprising at least one of the foregoing,below, and wherein the bi-functional compound comprises at least one ofa monomer with A and at least one of a monomer with B,

wherein A is a group represented by —OH or —X₂—R₁₁—Y₂ where X₂ is O—,—S—, —NR₁₂—, or a combination comprising at least one of the foregoing,where R₁₂ is hydrogen, halogen, a substituted or unsubstituted C₁-C₁₀alkyl, or a combination comprising at least one of the foregoing, R₁₁ isa substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, and Y₂ is —COOH,—SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing, B is a group represented by—X₃—R₁₃—Y₃ where X₃ is O—, —S—, —NR₁₄—, or a combination comprising atleast one of the foregoing, where R₁₄ is hydrogen, halogen, and asubstituted or unsubstituted C₁-C₁₀ alkyl, R₁₃ is a substituted orunsubstituted C₁-C₁₀ alkylene, a substituted or unsubstituted C₃-C₁₀cycloalkylene, a substituted or unsubstituted C₂-C₁₀ alkenylene, and asubstituted or unsubstituted C₂-C₁₀ alkynylene, or a combinationcomprising at least one of the foregoing, Y₃ is a group represented by

 where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic ring, or Y₃ is a group that is represented by

 and has a 4- to 8-membered alicyclic ring or a 6- to 8-memberedaromatic ring where R₆ and R₇ are each independently hydrogen, halogen,a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, R₈ is a substituted or unsubstituted C₁-C₁₀ alkylene, asubstituted or unsubstituted C₃-C₁₀ cycloalkylene, a substituted orunsubstituted C₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀alkynylene, or a combination comprising at least one of the foregoing,R₉ and R₁₀ are each independently hydrogen, halogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, wherein the bi-functional compound comprising Aand B has a polymerization degree of about 2 to about 30,000.
 6. Thesolid support of claim 5, wherein Q or Q₁ is a group represented by—X₁—R₁—Y₁ where R₁ is a C₁-C₁₀ alkylene, a C₃-C₁₀ cycloalkylene, aC₂-C₁₀ alkenylene, a C₂-C₁₀ alkynylene, or a combination comprising atleast one of the foregoing, each of the group being substituted with atleast one group of —COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻,or a combination comprising at least one of the foregoing, and B is agroup represented by —X₃—R₁₃—Y₃ where R₁₃ is a C₁-C₁₀ alkylene, a C₃-C₁₀cycloalkylene, a C₂-C₁₀ alkenylene, a C₂-C₁₀ alkynylene, or acombination comprising at least one of the foregoing, each of the groupbeing substituted with at least one group of —COOH, —SO₃H, —SO₂H, —SOH,—H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combination comprising at least one ofthe foregoing.
 7. The solid support of claim 5, wherein the first pH isabout 2 to about 5, and the second pH is about 7 to about
 12. 8. Thesolid support of claim 5, wherein Q or Q₁ is

or a combination comprising at least one of the foregoing, and B

or a combination comprising at least one of the foregoing.
 9. The solidsupport of claim 5, where the substrate is in the form of a planarplate, a multilayered structure, a non-planar structure includingsphere, bead, sieve, pillar or combination comprising these, or asurface of a microchannel in a microfluidic device.
 10. The solidsupport of claim 5, wherein substrate of the solid support on which thebi-functional compound is immobilized is glass, magnetic beads, silica,fused silica, polyethylene, polypropylene, polycarbonate, polyester,polyimide, slide glass, silicon wafer, SiO₂, TiO₂, Al₂O₃, SiN_(X),TiN_(X), sapphire, metals such as steel, aluminum, titanium, tantalum,silver, gold, platinum, SiO₂ or silicon substrates coated with one ofthese metals, oxides, or nitrides, or a combination comprising at leastone of the foregoing.
 11. The solid support of claim 10, where thesurface of the substrate has additional features or textures forincreasing surface area, the features comprising pits, holes, posts,grooves, linear or nonlinear lines and spaces, and combinations of theforegoing.
 12. A method of isolating a nucleic acid, the methodcomprising: contacting a bi-functional compound with a sample comprisinga nucleic acid at a first pH; and exposing the bi-functional compoundwith the nucleic acid bound thereto at a second pH that is higher thanthe first pH to release the nucleic acid from the bi-functionalcompound, the bi-functional compound being positively charged at a firstpH and negatively charged at a second pH, and represented by Formula Ibelow:Q-X-Q₁  (Formula I) wherein Q or Q₁ is a group represented by —X₁—R₁—Y₁where X₁ is —O—, —S—, or —NR₂— or a combination comprising at least oneof the foregoing, where R₂ is hydrogen, halogen, and a substituted orunsubstituted C₁-C₁₀ alkyl, R₁ is a substituted or unsubstituted C₁-C₁₀alkylene, a substituted or unsubstituted C₃-C₁₀ cycloalkylene, asubstituted or unsubstituted C₂-C₁₀ alkenylene, a substituted orunsubstituted C₂-C₁₀ alkynylene, r a combination comprising at least oneof the foregoing, Y₁ is a group represented by

 where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic group, or Y₁ is a group that is represented by

 and has a 4- to 8-membered alicyclic ring or a 6- to 8-memberedaromatic ring where R₆ and R₇ are each independently hydrogen, halogen,a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, at least one of Q and Q₁ has a primary or secondary aminogroup, X is a compound represented by

 wherein L is a bond, —O—, —CO—, —S—, —SO₂—, —CH₂—, —C(CH₃)₂—,—C(CF₃)₂—, or a combination comprising at least one of the foregoing,

 wherein the carbonyl group and the carboxyl group are substituted atany available carbon position except for a ring connection portion,

 or a combination comprising at least one of the foregoing, or abi-functional compound that is positively charged at a first pH andnegatively charged at a second pH, wherein the bi-functional compound islinked to at least one monomer comprising monomers represented by M0,M1, M2, M3, or a combination comprising at least one of the foregoing,below, and wherein the bi-functional compound comprises at least one ofa monomer with A and at least one of a monomer with B,

wherein A is a group represented by —OH or —X₂—R₁₁—Y₂ where X₂ is —O—,—S—, —NR₁₂—, or a combination comprising at least one of the foregoing,where R₁₂ is hydrogen, halogen, a substituted or unsubstituted C₁-C₁₀alkyl, or a combination comprising at least one of the foregoing, R₁₁ isa substituted or unsubstituted C₁-C₁₀ alkylene, a substituted orunsubstituted C₃-C₁₀ cycloalkylene, a substituted or unsubstitutedC₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀ alkynylene, ora combination comprising at least one of the foregoing, and Y₂ is —COOH,—SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combinationcomprising at least one of the foregoing, B is a group represented by—X₃—R₁₃—Y₃ where X₃ is O—, —S—, —NR₁₄—, or a combination comprising atleast one of the foregoing, where R₁₄ is hydrogen, halogen, and asubstituted or unsubstituted C₁-C₁₀ alkyl, R₁₃ is a substituted orunsubstituted C₁-C₁₀ alkylene, a substituted or unsubstituted C₃-C₁₀cycloalkylene, a substituted or unsubstituted C₂-C₁₀ alkenylene, and asubstituted or unsubstituted C₂-C₁₀ alkynylene, or a combinationcomprising at least one of the foregoing, Y₃ is a group represented by

 where R₃ and R₄ are each independently hydrogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, or R₃ and R₄ are bound to each other to form analicyclic or aromatic ring, or Y₃ is a group that is represented by

 and has a 4- to 8-membered alicyclic ring or a 6- to 8-memberedaromatic ring where R₆ and R₇ are each independently hydrogen, halogen,a substituted or unsubstituted C₁-C₁₀ alkyl, a substituted orunsubstituted C₃-C₁₀ cycloalkyl, a substituted or unsubstituted C₂-C₁₀alkenyl, a substituted or unsubstituted C₂-C₁₀ alkynyl, or a combinationcomprising at least one of the foregoing, with a proviso that R₆ is nothalogen, R₈ is a substituted or unsubstituted C₁-C₁₀ alkylene, asubstituted or unsubstituted C₃-C₁₀ cycloalkylene, a substituted orunsubstituted C₂-C₁₀ alkenylene, a substituted or unsubstituted C₂-C₁₀alkynylene, or a combination comprising at least one of the foregoing,R₉ and R₁₀ are each independently hydrogen, halogen, a substituted orunsubstituted C₁-C₁₀ alkyl, a substituted or unsubstituted C₃-C₁₀cycloalkyl, a substituted or unsubstituted C₂-C₁₀ alkenyl, a substitutedor unsubstituted C₂-C₁₀ alkynyl, or a combination comprising at leastone of the foregoing, wherein the bi-functional compound comprising Aand B has a polymerization degree of about 2 to about 30,000.
 13. Themethod of claim 12, wherein Q or Q₁ is a group represented by —X₁—R₁—Y₁where R₁ is a C₁-C₁₀ alkylene, a C₃-C₁₀ cycloalkylene, a C₂-C₁₀alkenylene, a C₂-C₁₀ alkynylene, or a combination comprising at leastone of the foregoing, each of the group being substituted with at leastone group of —COOH, —SO₃H, —SO₂H, —SOH, —H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or acombination comprising at least one of the foregoing, and B is a grouprepresented by —X₃—R₁₃—Y₃ where R₁₃ is a C₁-C₁₀ alkylene, a C₃-C₁₀cycloalkylene, a C₂-C₁₀ alkenylene, a C₂-C₁₀ alkynylene, or acombination comprising at least one of the foregoing, each of the groupbeing substituted with at least one group of —COOH, —SO₃H, —SO₂H, —SOH,—H₂PO₄, —HPO₄ ⁻, —PO₄ ²⁻, or a combination comprising at least one ofthe foregoing.
 14. The method of claim 12, wherein Q or Q₁ is

or a combination comprising at least one of the foregoing, and B

or a combination comprising at least one of the foregoing.
 15. Themethod of claim 12, wherein the first pH is about 2 to about 5, and thesecond pH is about 7 to about
 12. 16. The method of claim 12, whereinthe bi-functional compound is immobilized on substrate to form a solidsupport.
 17. The method of claim 16, wherein the substrate of the solidsupport is in the form of a planar plate, multilayered structure, anon-planar structure including a sphere, bead, sieve pillar, or acombination comprising at least one of the foregoing, or a surface of amicrochannel in a microfluidic device.
 18. The method of claim 16,wherein the substrate of the solid support on which the bi-functionalcompound is immobilized is glass, magnetic beads, silica, fused silica,polyethylene, polypropylene, slide glass, and silicon wafer, SiO₂, TiO₂,Al₂O₃, SiN_(X), TiN_(X), sapphire, metals such as steel, aluminum,titanium, tantalum, silver, gold, platinum, SiO₂ or silicon substratescoated with one of these metals, oxides, or nitrides, or a combinationcomprising at least one of the foregoing.
 19. The method of claim 12,wherein the first pH is about 3 to about 4.5, and the second pH about 7to about
 11. 20. The method of claim 12, wherein the first pH is about3.5 to about 4.5, and the second pH is about 8 to about
 11. 21. A solidsupport on which a bi-functional compound is immobilized, comprising thesequential reaction product of: a substrate, a surface treatment agent,a dianhydride or polyanhydride, and a nitrogen-containing compound,wherein the bi-functional compound is positively charged at a first pHand negatively charged at a second pH.